Apparatus and methods for handling strip material

ABSTRACT

Apparatus includes strip material supply means, a press, and a straightening roller stand (i.e., a straightener having rollers) disposed adjacent to a mechanical press or other material processing device to which strip material is introduced in discrete steps. The strip material is fed from a reel through straightening rollers and then to the press die set, with a slack loop of material in a temporary material storage locale between the straightening rollers and the die set. A positive displacement fluid motor is used to drive the straightener, the fluid motor being connected with fluid flow control means that in turn are controlled in synchronism with operation of the press or other material processing device. A supercharging pump maintains the fluid system charged while the pump, in effect, meters fluid to the motor. Hydraulic circuit means are provided to &#39;&#39;&#39;&#39;fine tune&#39;&#39;&#39;&#39; the hydraulic system and synchronize the fluid motor in a desired manner. Detector means are provided and control the slack loop to maintain it within predetermined limits. Means associated with the detector means operate to divert or otherwise control leakage fluid from the motor inlet when the slack loop exceeds a predetermined maximum length, and to supply additional fluid to the fluid motor inlet when the slack loop shortens to less than a predetermined minimum length.

United States Patent 1 Bair [ 1 Oct. 2, 1973 APPARATUS AND METHODS FORHANDLING STRIP MATERIAL [75] Inventor: Eugene C. Bair, Holland, Mich.

[73] Assignee: General Electric Company, Fort Wayne, Ind.

[22] Filed: Mar. 24, 1972 [21] Appl. No.: 237,827

Primary ExaminerMilton S. Mehr Attorney-John M. Stoudt et al.

[57] ABSTRACT Apparatus includes strip material supply means, a press,and a straightening roller stand (i.e., a straightener having rollers)disposed adjacent to a mechanical press or other material processingdevice to which strip material is introduced in discrete steps. Thestrip material is fed from a reel through straightening rollers and thento the press die set, with a slack loop of material in a temporarymaterial storage locale between the straightening rollers and the dieset. A positive displacement fluid motor is used to drive thestraightener, the fluid motor being connected with fluid flow controlmeans that in turn are controlled in synchronism with operation of thepress or other material processing device. A supercharging pumpmaintains the fluid system charged while the pump, in effect, metersfluid to the motor. Hydraulic circuit means are provided to fine tunethe hydraulic system and synchronize the fluid motor in a desiredmanner. Detector means are provided and control the slack loop tomaintain it within predetermined limits. Means associated with thedetector means operate to divert or otherwise control leak age fluidfrom the motor inlet when the slack loop ex ceeds a predeterminedmaximum length, and to supply additional fluid to the fluid motor inletwhen the slack loop shortens to less than a predetermined minimumlength.

19 Claims, 4 Drawing Figures United States Patent 1 m1 3,762,198

Bair v Oct. 2, 1973 APPARATUS AND METHODS FOR HANDLING STRIP MATERIALBACKGROUND OF THE INVENTION The present invention relates to apparatusand methods for handling strip material and, more particularly, tomethods and arrangements for driving a mechanism acting on a strip ofmaterial that is being fed to a mechanical press. Exemplifications ofthe invention embody hydrostatic drive arrangements for rollers actingon a strip and to means and methods for controlling the same.

In the formation of metal parts in a mechanical press as occurs, forexample, in the manufacture of stator and/or rotor laminations forelectric motors, a strip of steel is usually fed from a supply roll orreel through a set of dereeling or straightening rollers, e.g., toremove curvature from the strip as it approaches the press die set.Presses generally require an intermittent feed of material, with thestrip dwelling in the press while a stamping or other operation isperformed. However, it is generally more desirable for the stripmaterial to pay off the supply roll at a relatively uniform and constantspeed rate. The strip of material must, in such a case, pass throughrollers such as straightening rollers at a relatively constant anduniform speed even though the strip is moved intermittently past orthrough the die set in the press.

ln apparatus comprising a punch press and a roller straightener; thestraightening rollers usually include one or two driven feed rolls. Thedriving of the feed rolls may be accomplished by a mechanical connectionextending from the press crankshaft to the feed rolls or may beaccomplished by driving the feed rolls with a rotary motor, such as anelectric motor. The difficulty always presents itself, however, ofsynchronizing a desired continuous feed of the strip through thestraightening rollers with an intermittent movement of the strip throughthe die set in the press. A slack loop usually is left in the materialbetween the straightening roller set and the press, and variations inthis loop may be employed for varying the speed of rotation of the feedrolls. An eddy current clutch and brake control system heretoforeattempted for controlling the speed of the strip through thestraightening rollers has been considerably less flexible and lessreliable than has been desirable. Other systems, while being relativelyinexpensive, have been unsatisfactory, particularly for higher pressspeeds (and therefore material feed rates) and for applications thatrequire that substantially no stretching of the strip material occurbetween the supply reel and the press.

For example, in the manufacture of steel laminations for electricmotors, it is common to process strip steel so that reels of laminationsteel are provided. The strip steel on these reels will be partiallyprocessed, and be in the form of lamination blanks joined together by athin web of steel. Each blank in the strip will have one or more holestherein that, desirably, will be precisely located in a press die setwhen the press is operated to separate the lamination blanks from thestrip.

In many applications, the center of each lamination blank will have asingle hole in the center thereof which may be subsequently used toaccommodate a rotor shaft or the center of which will be the center of arotor accommodating stator bore. When this is the case, the holes willbe located precise preselected distances from one another in the stripand the press will pass this same preselected amount of steel throughthe press die set during each press stamping cycle.

If however, the strip material is stretched (i.e., elongated) betweenthe dereeling station and press station, the distance between laminationblank holes will be undesirably increased. In at least some applicationsin the past, roller straighteners have fed material to a storage loopuntil a mechanical, swingably mounted, arm bearing on the strip hasmoved to actuate a limit switch and stop the driven straightenerrollers. Then, as a press took material from the loop, the mechanicalarm would swing up as the loop diminsihed in size and the rollers wouldthen start and re-establish an oversized loop. Thus, the straightenerrollers would cyclically start and stop, and the strip material would bestressed as it was pulled in jerks from the supply reel. Stresses alsooccurred as a result of contact on the strip by the mechanical arm. Ihave concluded that a limitation on speed of press operation hasresulted from this, because at higher speeds of operation, thesestresses would cause an elongation of the strip steel, particularly inthe region of the webs between lamination blanks in the strip.

With the foregoing in mind, an object of the present invention is toprovide improved methods and apparatus for handling strip material.

Another object of the present invention is to provide methods andapparatus for synchronizing the continuous movement of strip materialinto a storage loop locale with an intermittent movement of stripmaterial away from the storage locale.

Still another object of the present invention is to provide methods andapparatus for driving strip material through a set of straighteningrollers for supply to a press, and for finely controlling the speed ofmovement of the strip material.

A more specific object of the present invention is to provide methodsand arrangements for substantially continuously driving one or morerolls of a straightening apparatus by hydraulic means that areresponsive to the operation of a press so that high speed pressoperation may be established and maintained without elongation orotherwise damaging strip material that extends between the straighteningapparatus and press.

Further objects and advantages of my invention will become apparent fromthe description hereinafter presented.

SUMMARY OF THE INVENTION In carrying out the above and other objects,the present invention is exemplified and practiced in one form thereof,with apparatus comprising strip supply means, a press, and astraightener having rollers disposed adjacent to a mechanical press towhich strip material is introduced. The strip material is fed from areel through straightening rollers and then to the press die set, with aslack loop of material in a temporary material storage locale betweenthe straightening rollers and the die set. A fluid motor is used todrive the straightener, the fluid motor being connected with fluid flowcontrol means that in turn are controlled in synchronism with pressoperation.

The fluid flow control means may be a positive displacement hydraulicpump and the fluid motor a positive displacement unit matched to thepump. A supercharging pump then is connected to the inlet side of thepump and maintains the fluid system charged while the pump, in effect,meters fluid to the motor. Hydraulic circuit means are provided to finetune" the hydraulic system and synchronize the fluid motor in a desiredmanner. Detector means are provided and control the slack loop tomaintain it within predetermined limits. Means associated with thedetector means operate to divert fluid from the motor inlet when theslack loop exceeds a predetermined maximum length, and to supplyadditional fluid to the fluid motor inlet when the slack loop shortensto less than a predetermined minimum length. The subject matter which Iregard as my invention is particularly pointed out and distinctlyclaimed in the concluding portion of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS The invention itself, however,together with further objects and advantages thereof may be bestunderstood by reference to the following detailed description taken inconjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view, schematically illustrating apparatuscomprising a mechanical press and a straightening roller stand andembodying my invention in one form, and which may be used to practice amethod exemplifying my invention;

FIG. 2 schematically illustrates a hydraulic circuit useful for adesired mode of operation of the apparatus of FIG. 1;

FIG. 3 is a perspective view showing the physical arrangement of some ofthe components of the hydraulic circuit of FIG. 2; and

FIG. 4 schematically illustrates an electric control circuit thatcontrols the operation of the hydraulic circuit of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawingssomewhat more in detail, in FIG. 1 a mechanical press is schematicallyindicated at and has mounted therein a die set 12 for operating onsegments of a strip of material, indicated at 14. Strip 14 consists of aseries of interconnected disc-like elements, each with a central hole.Within the die set, the elements are intermittently separated from eachother and punched to form laminations for an electric motor havingwinding accommodating slots therein. The strip 14 is fed from a reel 16of the material and passes from the reel through material handling meansillustrated as a straightening roller stand, generally indicated at 18.The straightener comprises a conventional arrangement of a pair ofsuperimposed rows of rollers which are staggered in the direction ofmovement of the strip 14. A set of feed rolls at the exit end of thestand grip or pinch the strip of material and pull it through the stand.The strip 14 is thus fed between the rollers, and the rollers serve tostraighten out the strip, removing any bend therein. Between thestraightening roller stand I8 and die set 12 there is a temporarymaterial storage locale at which is located slack loop 20 of the stripof material.

One or both of the feed rolls of the straightening stand 18 are drivenby means of a sprocket 22 which is connected with a motor drivensprocket 24 by a chain 26. A belt, preferably in the form of a timingbelt so as to prevent slipping between the belt and cogged pulleys ofcourse could also be used.

Pulley 24 is driven by a fluid motor 34 (best represented in FIGS. 2 and3). The fluid motor 34 is connected by conduits 28 and 30 in circuitwith suitable fluid supply means, e.g., a pump, metering valve means, ora pump used to meter a fluid. In the exemplification, the fluid supplymeans includes a fluid pump 32 mounted on press 10 and driven throughsuitable means in synchronism with the crankshaft of the press, e.g., bya timing belt or chain drive, so as to provide a positiveinterconnection between the fluid pump 32 and the press crankshaft.

FIG. 2 schematically illustrates the hydraulic circuit interconnectingfluid pump 32 and the fluid motor 34 which drives the feed rolls of thestraightening roller stand. The fluid motor 34 has the inlet sidethereof connected with the outlet side of pump 32 by conduit 28. Theinlet side of pump 32 is connected by conduit 30 with the discharge sideof a supercharging pump 36 which is driven by a motor 38. The suctionside of supercharging pump 36 is connected by conduit 40 to a filter 42located in a reservoir 44.

The discharge side of motor 34 is connected by conduit 46 through avalve 48 that acts as a relief valve and as a valve for decelerating andbraking motor 34. During operation of motor 34; valve 48 dischargesfluid through exhaust conduit 50 to a heat exchanger 52 to theaforementioned return conduit 40. For this type of operation, valve 48vents the hydraulic fluid with about 5 pounds per square inch backpressure from the motor 34 to the heat exchanger 52 where the fluid iscooled, and from which it then returns to the conduit 40. Valve 48 has apilot or control line 54 leading to a valve 56 that is controlled by asolenoid 8-1. The outlet side of valve 56 is connected by conduit 58 tothe reservoir 44. When solenoid S-l is energized, the control line 54 isopened so that fluid may freely pass from valve 48 through the controlline 54 back into the reservoir, and the valve 48 will still pass fluidabove 5 psi to line 50. However, 500 pounds per square inch pressure onthe inlet side of valve 48 is required for flow from line 46 throughvalve 48 when the control line 54 is closed by valve 56.

In this condition, valve 48 acts as a high pressure relief valve, andvents fluid from line 46 only when the pressure in line 46 exceeds about500 psi. This condition normally occurs when the press is stopping andit is desired to stop motor 34. It will be understood that it isdesirable to prevent freewheeling of motor 34 under this condition, sowhen solenoid S-l is deenergized, the inertia of motor 34 will cause abuild-up of pressure in line 46 and this in turn will cause motor 34 todecelerate and stop as the pump 32 stops with the press. Thus, with thesolenoid S-l deenergized, fluid passes through the valve 56 from theconduit 74 to the conduit 58. Under these circumstances conduit 54 isclosed and the valve 48 is held in its 500 pounds per square inch highpressure relief or venting state. When the solenoid S-l is againenergized, fluid passes from conduit 54 to conduit 58 and valve 48assumes its 5 pounds per square inch venting state.

It will be understood that pump 32 and motor 34, like other hydrauliccomponents, have engineered leaks to provide a flow of slippage orleakage fluid that is utilized as a means of internal lubrication.Accordingly, drain line 60 leads from each of pump 32 and motor 34 backto reservoir 44 and conveys such slippage or leakage fluid back to thereservoir by any suitable drain line.

Charging pump 36 may be by-passed by fluid flowing thru a safety checkvalve 62 that will permit fluid flow from the reservoir 44 to lines 64and 30 in the event that pump 36 should stop while pump 32 is stillbeing driven. This valve and a safety check valve 63 that is in aconduit parallel with the heat exchanger 52 function to prevent anyaccidental damage to their associated hydraulic circuit elements. Valve63 is normally set at about 30 or 40 psi to prevent damage to the heatexchanger in the event that it should become blocked. The downstreamsides of check valve 62 and charging pump 36 are connected to a conduit64 which is connected through a variable choke or flow control valve 66,a check valve 68, and a conduit 88 so that fluid is supplied to an inletport of a valve 70 which is controlled by solenoids S-2 and S3 for apurpose to be described hereinafter. Check valve 68 is provided as asafety feature for the hydraulic circuit to insure that back flow cannotoccur in line 88.

Conduit 64 is also connected to the inlet side of a pressure reliefvalve 72 which is set to open at a pressure of about 200 pounds persquare inch when its control or pilot conduit 74 is not vented back tothe reservoir 44 through valve 56. The conduit 74 is not vented to thereservoir when solenoid Sl of valve 56 is energized. The pressure levelfor relief valve 72 drops to around 90 pounds per square inch whensolenoid S-l is de-energized so that flow from line 74 to line 58through valve 56 occurs. The discharge side of valve 72 is connected toconduit 50.

Conduit 64 is also connected to a pressure indicating gauge 76 and apressure safety switch 78 set to close for pressures above apredetermined minimum pressure, e.g., above the low pressure setting ofvalve 72. The switch 78 then will open if pressure in line 64 dropsbelow a set minimum level.

The aforementioned valve 70 has a discharge port connected by conduit 80with conduit 28 and also with the inlet side of a pressure relief valve82. The valve 82 is set to open if excessive pressure builds up in line28. In the exemplification, if pressure in line 28 exceeds about 700 to800 pounds per square inch pressure, valve 82 will pass fluid from line28 and 80 to exhaust conduit 50. High pressure in line 28 may occur whenthe press starts and stops, for example. Valve 70 also has an exhaust ordischarge port through which fluid can discharge through conduit 84 andan adjustable choke or flow control valve 86 to reservoir 44.

Valve 70 is a three position valve and is normally in its centeredposition. When valve 70 is in its centered position and neither ofsolenoids S2, S3 is energized, all ports of valve 70 are closed so thatconduits 80, 84, and 88 are shut off from each other. Upon energizationof solenoid S3, valve 70 will shift to connect conduit 80 with conduit84, thereby permitting fluid to flow from conduit 28 through conduit 80and valve 70 to conduit 84 and then through choke or flow control valve86 to the reservoir 44. The flow control valve 86 is adjusted to obtainany desired controlled fluid bleedoff rate from the line 28. This thencontrols the rate at which motor 34 will slow down while solenoid S3 isenergized.

However, when solenoid S-2 is energized, valve 70 shifts and connectsconduit 88 with conduit 80 to supply additional fluid to conduits 80,28, and motor 34 from pump 36 through conduit 64, flow control valve 66,check valve 68, and conduit 88. The flow control valve 66 is adjusted toprovide the desired rate and amount of speed increase of motor 34 whilesolenoid S2 is energized.

Valve 56 is a two position valve and when no material is to be fed fromthe rollers 92 the valve 56 (with solenoid Sl de-energized) ispositioned to interconnect control or pilot conduit 74 and exhaustconduit 58, while closing off control conduit 54. Under thesecircumstances, valve 48 acts as a pressure relief valve and will notopen until the pressure in line 46 reaches about 500 pounds per squareinch. Thus, rotation of motor 34 is effectively prevented. Under thesesame circumstances relief valve 72 opens with a pressure in line 64 ofabout 90 pounds per square inch or more. Then fluid from charging pump36 flows through line 64, valve 72, line 50, and heat exchanger orcooler 52 to the reservoir 44. However, when solenoid 5-1 is energized,oil flow through pilot conduit 74 is cut off, pilot conduit 54 isconnected to exhaust conduit 58, and valve 48 switches to its opencondition with a back pressure on line 46 of about 5 pounds per squareinch. This permits motor 34 to rotate. Since valve 72 is effectivelyprevented from opening, the charging pump 36 will hold pressure of about250 pounds per square inch on lines 64 and 30. If the pressure in lines64 and 30 exceeds the desired 250 psi level, valve 72 will pass excessfluid from line 64 to line 50.

As will be seen from FIG. 2, pump 32 is drivingly connected as by timingbelt 88 with a rotary part of the press drive train, for example, thepress crankshaft 90. Thus, operation of pump 32 is exactly synchronizedwith the press and the shaft of pump 32 will turn a given fixed amountfor each and every stroke of the press. Moreover, faster strokes by thepress will cause faster movement of the pump 32. Accordingly, the volumeand rate of flow of fluid passing through pump 32 is preciselycontrolled by actual press operation. Similarly, the feed rolls 92 ofthe straightening roller stand are positively interconnected with motor34 by a timing belt and toothed pulleys or other means as describedabove.

Pump 32 and motor 34 are positive displacement units and may be, forexample, in the form of piston units. Accordingly, there issubstantially no slip in the hydraulic coupling of the pump 32 to themotor 34. Such pumps and motors can be relatively small and lightweightso that the response of the motor to rotation of the pump is extremelyrapid and full torque is developed on the motor relatively quickly.

In the arrangement illustrated or any other arrangement where theadvantages of the invention are to be obtained, a desired predeterminedspeed ratio may be established between the speed of rotation of primarypress driving element 90 and the driven feed rolls 92 of thestraightening roller stand. When this ratio is maintained, the rollers92 may be driven continuously to supply strip material at asubstantially constant and uniform rate to an intermediate loop ortemporary material storage locale while the press intermittently takesmaterial from the loop or temporary storage locale. It will beunderstood that this ratio may be quickly determined from the feed perstroke and strokes per minute for the press. For example, for steadystate operation with a feed of 6 inches of material per press stroke,and 10 press strokes per minute, the rollers 92 desirably willconstantly supply 60 inches of material per minute to the temporarystorage locale. Assuming that the driven roller 92 has a circumferenceof exactly l inches and that no slippage occurs between the stripmaterial and driven roller 92, the motor 34 would then desirably drivethe roller 92 at exactly four revolutions per minute. Accordingly, thedrive ratio between press member 90 and pump 32, and the drive motor 34and roller 92 would be selected to provide this desiredl performance.

Of course, occasional or even slight constant or variable slippagebetween roller 92 and the strip material will occur, and gears orsprockets with the exactly desired ratios may not be available. However,the exemplification herein disclosed includes various means that finetune the hydraulic system and compensate for factors such as this, allas will be hereinafter pointed out.

It will be understood that a change in the type of workpiece fed to thepress, a change in the desired amount of movement of the strip on eachcycle or stroke of the press, or a change in other factors usually willrequire a different rate of feed of the strip material through thestraightening roller stand. In these cases, the drive ratio to pump 32or drive ratio from motor 34, or both may be readily changed.

FIG. 2 shows a slack loop that establishes a temporary storage locale.The loop 20 is guided between a detector D1, which detects an excessamount of material in the loop and a detector D2 which detects a shortloop condition. These detectors may be any suitable type, e.g.,mechanical, optical, proximity, etc. For purposes of exemplification,commercially available mechanical and proximity detectors were used.Proximity detector D2 is mounted on an arm 94 pivoted at 96. If the arm96 is lifted by excessive shortening of the slack loop, still anotherdetector in the form of a limit switch LS1 is switched to an opencircuit condition for a purpose described later herein.

With continued reference to FIG. 2, conduit 28 is connected to anadjustable bleed or flow control valve 98 that discharges to thereservoir or sump 44. Under steady state running conditions of thesystem this bleed valve 98 can be fine tuned" to the point that thecontrol provided by one or the other of the detectors D1 and D2 willrarely be required. Use of the bleed valve 98 (or other means for asimilar result) is particularly desirable when the linkage between themotor 34 and the feed rolls 92 is, for example, a chain and sprocketarrangement whereby the speed ratio of the two sprockets can be changedonly by discrete steps.

For example, if for a given set of conditions, the feed rollers 92should in theory execute 1.98 revolutions for each revolution of pump32, sprockets would probably not be available to conveniently providethe desired drive ratios. For this condition, with pump 32 and motor 34being selected as substantially identical and matched units, a drivebetween motor 34 and roller 92 would be provided to drive roller 92 at a2 to 1 ratio relative to motor 34. The bleed valve 98 would then becarefully adjusted to bleed fluid from line 28 so as to provide thedesired drive ratio of roller 92 relative to pump 32. Also, duringcontinued operation, the valve 98 is used to fine tune" the system sothat relatively infrequent, if any, correction by detectors D1 and D2 isneeded.

For protection of pump 32, a safety device 300 is provided across linesor conduits and 28. This device is a pressure differential check valvewhich prevents direct fluid flow from line 30 to line 28. However, ifline 30 should rupture or the sump 44 should run dry and if pump 34should be operated under this condition; the valve 300 will circulateoil from line 28 (as it is discharged by pump 32) back to line 30 andthence to the inlet of pump 32.

FIG. 3 shows the manner in which the valves and other componentsreferred to in FIG. 2, including charging pump 36, electric motor 38,and fluid motor 34, are organized to fit within the base portion of acomercially available roller straightener of the type available from theF. .I. Littell Machine Company of Chicago, Ill. The motor 34, and thematching positive displacement pump 32 of FIG. 1, as well as many of theother components illustrated in FIG. 3 are commercially available items.The illustrated pump and motor are radial piston matched displacementdevices marketed as a Kawasaki Staffa type B-l0 motors by Kawasaki HeavyIndustries, Limited, Oil Hydraulic Machinery Division, Kobe, Japan. Theheat exchanger 52 was a Young type OCH-24 forced air radiator, and thepump 36a Delaval type 3-BI18. Five Double A control valves are shown inthe FIG. 3 embodiment. The Double A designations of the control valvesare: solenoid actuated valve 70, 2F-005C10-AILI(; solenoid actuatedvalve 56, QJ-0O5Pl0-AILK; valve 72, BT-O6K1OA2; valve 82, BT-06KIOA2;and valve 48, BT0610A2. Check valves 62 and 63 were Vickers valves,types C2815 and C2820 respectively. A manifold 97 was constructed andused for a base for the two solenoid actuated control valves 56 and 70.The manifold also was machined to provide the check valve 68 and thethree adjustable flow control valves 66, 86, and 98.

FIG. 4 schematically illustrated an electric control circuit that may beused to operate the valves and other apparatus shown in FIG. 2. In FIG.4, electric motor 38 will be seen to be controlled by contactors 108 ofa commercially available control in a conventional manner. A transformer102 energizes poser lines L1 and L2 of the control circuit when masterswitch 100, across a 60 Hz 220 volt line is closed. Between thesecondary of transformer 102 and line L1 is a circuit breaker 104 and anormally closed STOP" pushbutton 106.

A relay coil 108R that operates contactors 108 for control of motor 38is connected between lines L1 and L2 in series with a normally openSTART pushbutton 110 and thermally actuated motor overload contacts 109.Connected in pararllel with relay coil 108R is a fan motor 112 forcirculating air through the heat exchanger 52 and an indicating light114. This indicating light 114 is physically located on a small controlpanel of the straightener as illustrated in FIG. 1. The control panelalso contains the STOP switch 106, the START switch 110, a normallyclosed PRESS STOP switch 124, a JOG switch 128, a two-position selectorswitch 122 for automatic or manual press stroke operation, and a RUNswitch 118.

Connected in parallel with switch 110 is pressure switch 78 which isclosed so long as pump 36 maintains a desired pressure level in line orconduit 64 of FIG. 2. The normally open contacts 108a of motor starterrelay 108R are in series with switch 78. Switch 78 and contacts orblades 108a, when closed, connect line Llb and line L1.

Connected between lines Llb and L2 is the coil of relay coil 116 inseries with a normally open RUN" push-button switch 118. RUN pushbuttonswitch 118 is by-passed by a branch containing contacts 116a under thecontrol of relay coil 116, a normally open switch section 120 ofselector switch 122 and a normally closed switch section of STOPpushbutton 124. Switch 122 when adjusted for hand or manual operationhas its section 120 open and when adjusted for automatic operation hasits section 120 closed. Thus relay 116 functions as a latching relay andmaintains itself in an energized state by way of its own normally opencontacts 116a (which close when the coil of relay 116 is energized),provided the switch 122 is in its automatic position (with switch 120closed) and further provided that the normally closed PRESS STOP switch124 isclosed. The relay 116 then is latched by momentarily closing theRUN switch 118.

Also connected between lines Llb and L2 is a further branch containingthe coil of solenoid S-l (which, as will be recalled, controls valve 56in FIG. 2); switch section 126 of selector switch 122 and a normallyopen JOG" push-button switch 128. Switch section 126 is closed whenselector switch 122 is set for hand operation and is open when theselector switch 122 is set for automatic operation.

The serially arranged pushbutton JOG switch 128 and switch section 126are by-passed by a parallel circuit or branch containing normally openblades 116B under the control of relay coil 116 and contacts 130 thatare controlled by the control circuit for the press which is not shown.When the press is clutched in and running, contacts 130 will be closed;when the press is declutched, contacts 130 will be open. Solenoid S-1will be energized when relay 116 is energized, and the contacts 130 areclosed because of operation of the press; or when switch section 126 isclosed by setting the selector switch for hand or single cycleoperation, and switch 128 is closed by depressing the .106 button.Solenoid S-l is, of course, energized furing the normal runningoperation of the straightener motor 34, and deenergized when thestraightener is idle. Solenoid S-l is also energized when LOOP FEED"switch 203 is closed provided contacts 1168 are closed.

The circuit for similar proximity detectors D1 and D2 is schematicallyillustrated as being connected between lines Llb and L2. When detectorD1 is actuated indicating that the slack loop is too long, a coil ofrelay 132 is energized, and a holding circuit therefore is providedthrough contacts 1320 of relay 132 and normally closed contacts T2a of atimer T2. Similarly when the slack loop becomes too short, detector D2is actuated whereby relay 134 is energized and a holding circuittherefore is established through contacts 134a thereof and normallyclosed timer contacts Tla of a timer T1.

The timer T2 and a parallel resistor 136 are connected across lines Llband L2 by way of the normally closed contacts or blades 1341; of relay134, the normally open contacts 116d of relay 116, and the contacts 132bof relay 132. Forming yet another branch in parallel with the relaydevice or timer T2 is the coil of solenoid S-3 of control valve 70. Thetime device Tl has a similar parallel resistor 138, and that combinationis similarly in parallel with the coil or solenoid S-2 of the controlvalve 70, and this parallel combination of T1, 138, S-2 may be in closedcircuit relation across the lines Llb and L2 by either of two alternatebranches. The first branch comprises the normally open contact 128a ofthe JOG pushbutton while the other of the alternate branches comprisesthe series combination of the contacts 134a and 1160 of relays 134 and116 respectively.

As an example, assume that the detector D1(which may, with detector D2,be a General Electric type CR1 15Dl 1 18 time delay proximity sensor)detects that the loop 20 is longer than desired. The detector D1 willenergize the relay 132 and contact 132a will close, thus forming aholding circuit for the relay 132 by way of its own contact 1320 and thenormally closed contact T2a of a variable time delay device T2. T1 andT2 in the illustrated embodiment are identical adjustable time delaystructures having normally closed contacts which open a desiredpredetermined time interval (e.g., 10 seconds) after their initialenergization, and may be of the Eagle CGl0A6 type. Since under normalrunning conditions the solenoid S-l, the relay 108R, and the relay 116are always energized, time relay T2 will be energized through thenormally closed contact 134b, closed contacts 116d or relay 116, andcontacts l32b of relay 132 which close when a long loop is sensed by D1.The solenoid S-3 will be energized at the same time as the time delaydevice T2. Energizing solenoid S-3 allows some of the hydraulic fluid toby-pass the motor 34 of FIG. 2 by going downwardly into conduit throughvalve 70, down conduit 84, through control valve 86, back to thereservoir. This additional leakage will, of course, slow the motor 34somewhat, the press will take up some of the slack loop 20, and thuscorrect the originally detected long loop condition. After theprescribed time delay (e.g., 10 seconds) delay device T2 will open itscontact T2a thus deenergizing relay 132 and causing the contacts 132aand 1321: of relay 132 to open. Opening of contacts 132b alsode-energizes the solenoid S-3. Delay device T1 is energized in a verysimilar manner when the detector D2 indicates that the slack loop 20 istoo short, however, it should also be noted that contacts 128a may bemanually momentarily closed to provide a manual correction and thussupply additional material from the straightener upon demand by theoperator. This may be done, e.g., when strip material is first fed tothe press.

A portion of the press control circuit is shown at the bottom of FIG. 4and includes a series circuit loop containing switch section LSlA oflimit switch LS1, contacts l08b and contacts 124b. Section LSlA opens ifthe slack loop of strip material becomes dangerously short, contacts108b open if relay 108R drops out, and contacts 124b open if PRESS STOPswitch 124 is pressed. If any of these events occur, the electricalcontinuity between terminals 201 and 202 through the illustrated circuitloop is broken. Also, since terminals 201 and 202 are connected to thenot shown press circuit, this will cause the press to declutch and stopusing strip material.

When the press is declutched, contacts 130 will open. It should be notedthat if limit switch LS1 is moved so that contacts LSlA open, contactsLSlB will close. Since contacts LSlB, upon closing, shunt contacts 130,opening of contacts 130 will not de-energize solenoid S-1 and cause thesystem pressure to drop, switch 78 to open, and motor 34 to brake andstop. Also assuming that the press is declutched so that the contacts130 are open and further assuming that limit switch LS1 is not actuatedso that contacts LSlB will remain open,

the motor 34 may be conditioned to run by manually closing the contacts203 of the LOOP FEED switch. When this is done, solenoid 8-1 will beenergized through manually closed contacts 203 so long as relay 116remains energized and contacts 116B thereof are closed. Thus, contacts203 and 128a may be manually closed to feed material to the press whilethe press is declutched when switch 122 is set to automatic run andcontacts 126 are open.

For operation, contactor 100 and switch 110 are closed to therebyenergize motor 38 to drive pump 36 and also to energize the controlsystem. Should it be necessary to advance the strip to adjust the slackloop, or to feed a strip of new material to the straightener, JOGpushbutton 128 can be used. With solenoid S-1 energized, control valve56 causes fluid system pressure to rise, and pressure switch 78 closes.Actuation of JOG switch 128 energizes solenoid 8-1 of valve 56 and thuspermits relief valve 48 to operate and also shuts off relief valve 72.Also, solenoid 8-2 is energized (when 106 contacts 128a are closed) toshift valve 70, thereby to cause motor 34 to rotate in a direction tofeed strip material into the slack loop locale. When the slack loop isof the proper length, operation of the press is initiated by firstclosing RUN" switch 118 which will energize relay 116, and cause closingof contacts 116a, 116b, 116C, and 116d. If hand operation of the pressis desired, switch 122 is positioned with contacts 120 thereof open, andcontacts 126 thereof closed. Relay 116 then will not hold in, and theautomatic system will not function to control the slack loop sincecontacts 1 160 and 1 16d will be open. if automatic operation of thepress is desired, switch 122 is adjusted to close its contacts 120 andopen its contacts 126, so that relay 116 will hold or lock in, and theautomatic system will function. in either case, when the press controlis started and clutched in, contacts 130 will close to energize solenoidS-1 and shift valve 56 as previously described. Alternatively, solenoidS-I may be energized, by manually holding contacts 203 closed to shuntcontacts 130 as previously described.

When the press is running on automatic cycle and contacts 1168, 116a,and 116d are closed, the detectors D1, D2 will control the shifting ofvalve 70 so that if the slack loop becomes too long, solenoid 8-3 willenergize valve 70 so as to by-pass fluid away from motor 34, while ifthe slack loop grows too short solenoid 8-2 will be energized and shiftvalve 70 so as to supply additional fluid to motor 34.

The timers T1 and T2 control the length of time that the adjustingoperations continue after the detectors operate and may be setfor adesired time delay period.

lf the slack loop shortens dangerously for some reason, and thecompensation provided by a correction initiated by sensor or detector D2is not sufficient to remedy the condition, limit switch LS1 will opencontacts LSlA because of movement of arm 94. This will interrupt thepress control circuit as previously described. Similarly, pressing ofSTOP switch 124 to open its contacts 12412 or deenergization of relay108R to open its contacts 108b will also interrupt the press controlcircuit. Of course, depressing STOP" pushbutton 106 will interrupt theentire circuit, including the press control circuit.

From the foregoing, it will be appreciated that apparatus or methodsembodying the invention may be utilized to substantial advantage. Forexample, approxiestablish a material feed rate that will substantiallyequal the material utilization rate of the press. Thus, slippage betweena driven straightener roller and strip material; inability toeconomically establish theoretical gearing ratios; and amount ofmaterial on the supply reel; may be easily compensated for.

It should be apparent to those skilled in the art, while there has beenshown and described what at present is considered to be preferredembodiments of the invention, modifications can be made withoutdeparting from the spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A control circuit for synchronizing first and second materialprocessing devices which sequentially operate on a common length ofmaterial comprising: first and second fixed displacement hydraulicdevices coupled respectively to the first and second material processingdevices and each adapted to pass a volume of fluid which bearssubstantially the same relationship to the length of material operatedon by the respective processing device; and means hydraulicallyinterconnecting said first and second fixed displacement hydraulicdevices and adapted to introduce a controlled leakage into the hydraulicsystem to correct for differences in the respective rates of consumptionof material of the first and second material devices introduced by smalldifferences between said relationships.

2. The control circuit of claim 1 wherein said first device suppliesmaterial at a substantially constant rate and the second device consumesmaterial in discrete steps.

3. The method of operating the strip feeding means pertaining to astraightening roller stand to maintain a substantially fixed length ofslack loop in the strip of material between the straightening rollerstand and the machine being supplied thereby comprising: driving apositive displacement hydraulic pump by the machine; connecting apositive displacement motor to the strip feeding means; hydraulicallyinterconnecting the pump and the motor; and introducing a controlledamount of leakage between the pump and the motor to thereby slow themotor slightly and make the average rate of supply of strip materialfrom the feeding means more nearly the same as the average rate ofconsumption of the strip of material by the machine.

4. The method of claim 3 wherein the strip feeding means suppliesmaterial at a constant rate and the machine being supplied therebyconsumes material in discrete steps.

5. The method of claim 3 further comprising the steps of: sensing forexcessive variations in the length of the slack loop; introducingadditional leakage between the pump and the motor when the slack loopexceeds a predetermined maximum length; and introducing additionalhydraulic fluid between the pump and the motor when the slack loop isless than a predetermined minimum length.

6. ln combination; a machine having a member movable for operating onstrip workpiece material fed into the machine at one side, said machinehaving a rotary element rotatable in unison with movement of saidmember, a straightening roller stand spaced from said machine on saidone side thereof and having rotatable feed means and adapted to performstraightening operation on workpiece material while feeding theworkpiece material toward said machine, and a hydrostatic transmissioncomprising a pumping element drivingly connected to said rotary elementand a motor element drivingly connected to said feed means, andhydraulic conduit means connecting said elements in circuit.

7. The invention of claim 6 in which said hydraulic conduit meanscomprise a main conduit connecting the outlet of said pumping element tothe inlet of said motor element, and control means for varying the rateof supply of fluid to the inlet of said motor element.

8. The invention of claim 7 in which said control means includes anadjustable restricter connected between said main conduit and exhaust.

9. The invention of claim 7 in which said control means includes a firstcontrol valve connected to said main conduit, a variable flow controlvalve connected between said main conduit and exhaust; means forsupplying high pressure fluid to said pumping element; said firstcontrol valve having ports connected to the high pressure fluid andexhaust, respectively; and means for shifting said first control valveto selectively supply or subtract fluid from said main conduit.

10. The invention of claim 9 further including actuating means for saidfirst control valve, said actuating means including time delay meansoperable to maintain said first control valve in a selected actuatedposition for a predetermined time period following actuation thereof.

11. A first device for substantially continuously feeding stripmaterial; a second device located in spaced relation to the first devicefor intermittently performing a work operation on segments of stripmaterial supplied by the first device; and means for controlling theoperation of the first device in response to the operating condition ofthe second device; said means for controlling comprising: a firsthydraulic mechanism interconnected with the second device; a rotaryfluid motor drivingly connected to the first device; and hydrauliccircuit means interconnecting the first hydraulic mechanism and therotary fluid motor; said first hydraulic mechanism being operative tocontinuously supply hydraulic fluid to said hydraulic circuit meanscontinuously during continuous operation of the second device andintermittently during intermittent operation of said second device; saidrotary fluid motor operating in response to fluid supplied theretothrough said hydraulic circuit means to thereby drive the first deviceso that a predetermined amount of strip material, sufficient in lengthto permit continued operation of the second device, will be suppliedfrom said first device to said second device.

12. The structure of claim 11 wherein the first hydraulic mechanismcomprises a positive displacement unit interconnected by a slip freedriving connection with the second device; said rotary fluid motorcomprises a positive displacement unit; and said hydraulic circuit meansincludes means for continuously diverting a portion of the fluid movinginto the hydraulic circuit means away from the rotary fluid motor sothat under steady state continuous operating conditions, less fluid willmove through the rotary fluid motor than is supplied to the hydrauliccircuit means.

13. The structure of claim 11 wherein-the hydraulic circuit meansincludes control means for selectively increasing and decreasing theamount of fluid supplied to the rotary fluid motor.

14. The structure of claim 13 wherein the first device supplies stripmaterial to a temporary storage locale, the second device withdrawsstrip material from the temporary storage locale; sensing means areprovided for detecting over-supplied and undersupplied conditions of thetemporary storage locale; and wherein the detecting means areinterconnected with said control means for selectively increasing anddecreasing the amount of fluid supplied to the rotary fluid motor.

15. A method of operating strip feeding means to substantially maintaina predetermined amount of strip material in a slack loop between thestrip feeding means and a machine being supplied thereby, the methodcomprising: controlling fluid metering means by the machine beingsupplied; supplying high pressure fluid from the fluid metering meanstoward a positive displacement rotary motor and thereby driving thestrip feeding means; and diverting high pressure fluid from the rotarymotor to establish a preselected basic speed ratio between operation ofthe machine being supplied and the rotary motor.

16. The method of claim 15 further including detecting an undersupply ofstrip material in the slack loop and supplying high pressure fluid inaddition to that supplied from the fluid metering means to the rotarymotor.

17. The method of claim 15 further including positively driving themetering means in synchronism with operation of the machine beingsupplied; detecting an oversupply of strip material in the slack loop,and diverting more high pressure fluid from the rotary motor to therebyreduce the drive speed of the strip feeding means.

18. The method of claim 15 wherein the machine is a punch press and thestrip feeding means is a stock straightener.

19. The structure of claim 11 wherein the first device is a straightenerand the second device is a punch press.

1. A control circuit for synchronizing first and second materialprocessing devices which sequentially operate on a common length ofmaterial comprising: first and second fixed displacement hydraulicdevices coupled respectively to the first and second material processingdevices and each adapted to pass a volume of fluid which bearssubstantially the same relationship to the length of material operatedon by the respective processing device; and means hydraulicallyinterconnecting said first and second fixed displacement hydraulicdevices and adapted to introduce a controlled leakage into the hydraulicsystem to correct for differences in the respective rates of consumptionof material of the first and second material devices introduced by smalldifferences between said relationships.
 2. The control circuit of claim1 wherein said first device supplies material at a substantiallyconstant rate and the second device consumes material in discrete steps.3. The method of operating the strip feeding means pertaining to astraightening roller stand to maintain a substantially fixed length ofslack loop in the strip of material between the straightening rollerstand and the machine being supplied thereby comprising: driving apositive displacement hydraulic pump by the machine; connecting apositive displacement motor to the strip feeding means; hydraulicallyinterconnecting the pump and the motor; and introducing a controlledamount of leakage between the pump and the motor to thereby slow themotor slightly and make the average rate of supply of strip materialfrom the feeding means more nearly the same as the average rate ofconsumption of the strip of material by the machine.
 4. The method ofclaim 3 wherein the strip feeding means supplies material at a constantrate and the machine being supplied thereby consumes material indiscrete steps.
 5. The method of claim 3 further comprising the stepsof: sensing for excessive variations in the length of the slack loop;introducing adDitional leakage between the pump and the motor when theslack loop exceeds a predetermined maximum length; and introducingadditional hydraulic fluid between the pump and the motor when the slackloop is less than a predetermined minimum length.
 6. In combination; amachine having a member movable for operating on strip workpiecematerial fed into the machine at one side, said machine having a rotaryelement rotatable in unison with movement of said member, astraightening roller stand spaced from said machine on said one sidethereof and having rotatable feed means and adapted to performstraightening operation on workpiece material while feeding theworkpiece material toward said machine, and a hydrostatic transmissioncomprising a pumping element drivingly connected to said rotary elementand a motor element drivingly connected to said feed means, andhydraulic conduit means connecting said elements in circuit.
 7. Theinvention of claim 6 in which said hydraulic conduit means comprise amain conduit connecting the outlet of said pumping element to the inletof said motor element, and control means for varying the rate of supplyof fluid to the inlet of said motor element.
 8. The invention of claim 7in which said control means includes an adjustable restricter connectedbetween said main conduit and exhaust.
 9. The invention of claim 7 inwhich said control means includes a first control valve connected tosaid main conduit, a variable flow control valve connected between saidmain conduit and exhaust; means for supplying high pressure fluid tosaid pumping element; said first control valve having ports connected tothe high pressure fluid and exhaust, respectively; and means forshifting said first control valve to selectively supply or subtractfluid from said main conduit.
 10. The invention of claim 9 furtherincluding actuating means for said first control valve, said actuatingmeans including time delay means operable to maintain said first controlvalve in a selected actuated position for a predetermined time periodfollowing actuation thereof.
 11. A first device for substantiallycontinuously feeding strip material; a second device located in spacedrelation to the first device for intermittently performing a workoperation on segments of strip material supplied by the first device;and means for controlling the operation of the first device in responseto the operating condition of the second device; said means forcontrolling comprising: a first hydraulic mechanism interconnected withthe second device; a rotary fluid motor drivingly connected to the firstdevice; and hydraulic circuit means interconnecting the first hydraulicmechanism and the rotary fluid motor; said first hydraulic mechanismbeing operative to continuously supply hydraulic fluid to said hydrauliccircuit means continuously during continuous operation of the seconddevice and intermittently during intermittent operation of said seconddevice; said rotary fluid motor operating in response to fluid suppliedthereto through said hydraulic circuit means to thereby drive the firstdevice so that a predetermined amount of strip material, sufficient inlength to permit continued operation of the second device, will besupplied from said first device to said second device.
 12. The structureof claim 11 wherein the first hydraulic mechanism comprises a positivedisplacement unit interconnected by a slip free driving connection withthe second device; said rotary fluid motor comprises a positivedisplacement unit; and said hydraulic circuit means includes means forcontinuously diverting a portion of the fluid moving into the hydrauliccircuit means away from the rotary fluid motor so that under steadystate continuous operating conditions, less fluid will move through therotary fluid motor than is supplied to the hydraulic circuit means. 13.The structure of claim 11 wherein the hydraulic circuit means includescontrol means for selectively increasing and decreasing the amount Offluid supplied to the rotary fluid motor.
 14. The structure of claim 13wherein the first device supplies strip material to a temporary storagelocale, the second device withdraws strip material from the temporarystorage locale; sensing means are provided for detecting over-suppliedand undersupplied conditions of the temporary storage locale; andwherein the detecting means are interconnected with said control meansfor selectively increasing and decreasing the amount of fluid suppliedto the rotary fluid motor.
 15. A method of operating strip feeding meansto substantially maintain a predetermined amount of strip material in aslack loop between the strip feeding means and a machine being suppliedthereby, the method comprising: controlling fluid metering means by themachine being supplied; supplying high pressure fluid from the fluidmetering means toward a positive displacement rotary motor and therebydriving the strip feeding means; and diverting high pressure fluid fromthe rotary motor to establish a preselected basic speed ratio betweenoperation of the machine being supplied and the rotary motor.
 16. Themethod of claim 15 further including detecting an undersupply of stripmaterial in the slack loop and supplying high pressure fluid in additionto that supplied from the fluid metering means to the rotary motor. 17.The method of claim 15 further including positively driving the meteringmeans in synchronism with operation of the machine being supplied;detecting an oversupply of strip material in the slack loop, anddiverting more high pressure fluid from the rotary motor to therebyreduce the drive speed of the strip feeding means.
 18. The method ofclaim 15 wherein the machine is a punch press and the strip feedingmeans is a stock straightener.
 19. The structure of claim 11 wherein thefirst device is a straightener and the second device is a punch press.